This invention has utilization in all applications with piezoelectric valves utilizing piezoceramic elements or diaphragms.
A new gas delivery system is being designed to inject either tritium, hydrogen, or deuterium gas with uniform throughput for up to 6 seconds into the Tokamak Fusion Test Reactor (TFTR) Neutral Beam Long Pulse Ion Sources, at Princeton University.
Several experiments have been conducted to verify design concepts and qualify components. Piezoelectric valves were characterized for hydrogen and deuterium gas and the data used to predict operation with tritium. The uniformity of the gas throughput was studied as a function of test fluid, flow rate and initial supply pressure. The uniformity of the throughput with an active pressure feedback controller was tested under various operational scenarios. The functionality of a prototypical NB D-T Gas Delivery System has been tested and the results analyzed.
FIG. 2 illustrates, a typical, or prior-art, piezoelectric valve 20 that can be used for delivering tritium or deuterium gas in the Tokamak Fusion Test Reactor at Princeton University. The valve 20 is a commercially available piezoelectric valve manufactured by Maxtek Inc., which has been modified to handle hazardous and radioactive gases. The valve 20 includes a piezoceramic element 22 that is bonded to a seal 24 that together are disposed over an adjustable seat 26. The valve also includes a sapphire insulating ball 28 held in place by a preload spring 29. Gas flows into the valve 20 through gas inlet port 30. As can be seen the inlet port 30 flows into a volume bounded by the underside 32 of piezoceramic element 22, i.e. on the same side with the seal 24. Additional by-pass port 34, for gas flow around the piezoceramic element 22, was expected to help equalize pressure on the piezoceramic element.
It is a purpose of the present invention to provide a piezoelectric valve suitable for use in a neutral beam deuterium-tritium gas delivery system.
Another purpose of the present invention is to provide a piezoelectric valve that helps to equalize pressure on the piezoceramic element such that it positively seats.